Cochrane in CORR ®: Surgical Versus Non-surgical Treatment for Lumbar Spinal Stenosis

Importance of the Topic Lumbar spinal stenosis (LSS), an age-related degenerative narrowing of the spinal canal, results in considerable morbidity particularly in older patients. Patients typically present with low-back pain and activity-related leg pain that restricts their function and quality of life [3]. The socioeconomic burden of treating this pathology is tremendous [4], highlighting the need to improve effective treatment strategies in the management of this growing demographic. Nonsurgical interventions, including pain medications and physical therapy, are the first line of treatment in patients with LSS [8]. When indicated, surgical treatment of neurogenic claudication due to LSS may dramatically improve health-related quality of life [1]. However, complications sometimes follow surgery, particularly spinal instability resulting in fusion. In fact, reoperation rates as high as 27% in the first postoperative year have been reported [11]. This recent Cochrane Review compared surgical and nonsurgical treatments, and included randomized and quasirandomized controlled trials [13]. Based on the five trials (643 patients) that met inclusion criteria, the authors concluded that there are no clear benefits to surgery over nonsurgical treatment for patients with LSS. Upon Closer Inspection Substantial heterogeneity in populations and interventions was a major limitation of this Cochrane review. First, although all of the trials included patients with LSS, the standard for diagnosis and classification of LSS [10] was not clearly defined and thus the pooled patient groups likely were not homogenous. Second, nonsurgical treatment options differed considerably across trials, including a mix of physical therapy, home exercises, epidural steroid injections, pain medications, and various other modalities without a standardized protocol. Third, there was considerable variability in the surgical treatments used, including a combination of decompression, decompression and fusion, and use of an interspinous spacer in one study [11]. Results from this meta-analysis of two studies [9, 12] showed no important differences in function at 6 months and 1 year, but found a sizeable difference favoring surgery at 2 years. Despite considerable heterogeneity at 6 months (I2 = 72%) and 1 year (I2 = 81%), no exploration of heterogeneity was performed. Although the authors performed a random-effects model, heterogeneity in systematic reviews should still be explored and explained with a priori subgroup analyses or posthoc sensitivity analyses, which may reveal poor study design and study characteristics or “real” sources of variation related to patients, interventions, or outcome measures [5]. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria for systematic reviews requires a clear specification of the population, intervention, and comparators [6]. Additionally, the underlying biology must suggest that across the population and interventions, it is plausible that the magnitude of effect on the key outcomes is similar [6]. When multiple options are combined in the treatment arm (in this case, decompression, decompression and fusion, or interspinous spacer) or control arm (here, no treatment, pharmacologic treatment, physical therapy, or a combination) in meta-analysis, authors should specify whether all treatments are equally recommended or if some treatments are recommended over others [6]. If heterogeneous patient populations and interventions are pooled with no further explanation of heterogeneity, the review may generate misleading estimates with limited clinical applicability. Take-Home Messages This systematic review and meta-analysis found no clear benefit of surgery versus nonsurgical treatment, but the quality of the evidence for all outcomes was graded low due to high risk of bias, study design, and imprecision due to incomplete outcome data. According to the GRADE approach, low-quality evidence indicates little confidence in the effect estimate and that the true effect is likely to be substantially different from the estimate of effect [2]. Now with 8-year results, the Spine Patient Outcomes Research Trial (SPORT) represents the largest and highest-quality study available to isolate spinal stenosis from stenosis secondary to degenerative spondylolisthesis [7, 12]. SPORT was included in this Cochrane review and constituted a significant proportion of patients in the meta-analysis (289 of 383 patients). In this rigorous study that compared surgical versus nonsurgical care for LSS, patients could choose between randomization or enrollment in an observational arm. Intent-to-treat analyses showed no difference between randomized cohorts; further, although the as-treated analyses showed the early benefit for surgery out to 4 years, no substantial treatment effect of surgery was seen in years 6 to 8 for any of the primary outcomes [7]. In contrast, the observational cohort showed a stable advantage for surgery in all outcomes up to 8 years. This may be due to greater baseline differences in the two groups; long-term results in the as-treated trial are less likely to be confounded by baseline differences, suggesting that the advantage of surgery may diminish over time. Although this Cochrane review and the SPORT trial are not without limitations, their analyses call into question the long-term efficacy of surgical treatment for LSS. Clinicians need to carefully inform patients with LSS the potential limitations of surgery, especially given that no side effects were reported with nonsurgical treatment.

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